CompTIA Server+ (SK0-005)TroubleshootingMedium
A technician is troubleshooting a server that is experiencing intermittent network connectivity. The server's network interface card (NIC) link lights are flickering rapidly, but the activity light is mostly dark, even during attempted data transfers. The switch port it's connected to shows similar behavior. Other servers on the same switch port group are functioning normally. Which of the following is the MOST likely cause?
- AFaulty network cable
- BDuplex mismatch between the server and the switch
- CIP address conflict
- DIncorrect VLAN tagging on the server NIC
Show answer & explanationAnswer & explanation
Correct answer: A. Faulty network cable
Flickering link lights with minimal activity, especially when other devices on the same switch are working, often points to a physical layer issue. A faulty network cable can cause intermittent connectivity and signal integrity problems, leading to link status fluctuations without proper data flow.
Why the other options are wrong
- B. Duplex mismatch usually results in very slow, consistent, and high error rates, not necessarily rapidly flickering link lights with dark activity, although it can cause connectivity issues.
- C. An IP address conflict would result in connection drops or complete inability to communicate, but typically wouldn't manifest as flickering link lights without data activity.
- D. Incorrect VLAN tagging would typically prevent any connectivity beyond the server itself, or cause traffic to be misdirected, not intermittent link light flickering.
Faulty Network Cable
A damaged or improperly terminated network cable can cause intermittent connectivity, signal loss, and erratic link status indicators.
- Common cause of physical layer network issues.
- Can lead to packet loss and reduced throughput.
- Often indicated by unstable link/activity lights.
Memory trick: Cable's the culprit when lights go crazy.